using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Security.Cryptography;
using System.Text;

namespace Ant.Service.Common.CryptHelper
{
    public class DESCrypt
    {
         #region  ========算法========
        private static string key;//密钥
        static DESCrypt()
        {
            key = System.Configuration.ConfigurationManager.AppSettings["deskey"].ToString();
        }
        private static byte[] Keys = new byte[] { 0x12, 0x34, 0x56, 120, 0x90, 0xab, 0xcd, 0xef };//8个bit位，是DES算法的初始化向量  加解密钥也是8位;
        /// <summary>
        /// 解密字符串
        /// </summary>
        /// <param name="decryptString">是要被解密的密文数据</param>
        /// <param name="decryptKey">DES算法的工作密钥</param>
        /// <returns>明文</returns>
        public static string Decrypt(string decryptString, string decryptKey)
        {
            try
            {
                decryptKey = Utils.GetSubString(decryptKey, 8, "");
                decryptKey = decryptKey.PadRight(8, ' ');
                byte[] bytes = Encoding.UTF8.GetBytes(decryptKey);
                byte[] keys = Keys;
                byte[] buffer = Convert.FromBase64String(decryptString);
                DESCryptoServiceProvider provider = new DESCryptoServiceProvider();
                MemoryStream stream = new MemoryStream();
                CryptoStream stream2 = new CryptoStream(stream, provider.CreateDecryptor(bytes, keys), CryptoStreamMode.Write);
                stream2.Write(buffer, 0, buffer.Length);
                stream2.FlushFinalBlock();
                return Encoding.UTF8.GetString(stream.ToArray());
            }
            catch
            {
                return "";
            }
        }

        /// <summary>
        /// 加密
        /// </summary>
        /// <param name="decryptString">要被加密数据</param>
        /// <param name="decryptKey">DES算法的工作密钥</param>
        /// <returns>密文</returns>
        public static string Encrypt(string encryptString, string encryptKey)
        {
            encryptKey = Utils.GetSubString(encryptKey, 8, "");
            encryptKey = encryptKey.PadRight(8, ' ');
            byte[] bytes = Encoding.UTF8.GetBytes(encryptKey.Substring(0, 8));
            byte[] keys = Keys;
            byte[] buffer = Encoding.UTF8.GetBytes(encryptString);
            DESCryptoServiceProvider provider = new DESCryptoServiceProvider();
            MemoryStream stream = new MemoryStream();
            CryptoStream stream2 = new CryptoStream(stream, provider.CreateEncryptor(bytes, keys), CryptoStreamMode.Write);
            stream2.Write(buffer, 0, buffer.Length);
            stream2.FlushFinalBlock();
            return Convert.ToBase64String(stream.ToArray());//Base64是网络上最常见的用于传输8Bit字节代码的编码方式之一,Base64要求把每三个8Bit的字节转换为四个6Bit的字节（3*8 = 4*6 = 24），然后把6Bit再添两位高位0，组成四个8Bit的字节。
            //Base64编码可用于在HTTP环境下传递较长的标识信息,如较长的唯一标识符（一般为128-bit的UUID）编码为一个字符串，用作HTTP表单和HTTP GET URL中的参数，或者将二进制数据编码为适合放在URL（包括隐藏表单域）中的形式。此时，采用Base64编码不仅比较简短，同时也具有不可读性，即所编码的数据不会被人用肉眼所直接看到。
        }
        #endregion

         #region ========加密========

        /// <summary>
        /// 加密
        /// </summary>
        /// <param name="Text"></param>
        /// <returns></returns>
        public static string Encrypt(string Text)
        {
            return Encrypt(Text, key);
        }
        #endregion

         #region ========解密========

        /// <summary>
        /// 解密
        /// </summary>
        /// <param name="Text"></param>
        /// <returns></returns>
        public static string Decrypt(string Text)
        {
            return Decrypt(Text, key);
        }
        #endregion
    
    }
}